Debunking An Old Myth About Lightning

When I was younger, my father used to tell me during lightning storms that if you counted the seconds after lightning struck until you heard the thunder, that would tell you how far away the bolt of lightning was. Which is actually true, but not quite the way he suggested. You see, most people think that the seconds translate directly to miles. In other words, counting five seconds after a strike means the bolt is five miles away. This is incorrect as a little math will show.

Sound is known to travel through the atmosphere at approximately 768 miles per hour at sea level (with possible minor variations due to temperature and pressure). Knowing this, we can deduce how far sound waves travel every second. Take out your calculator and type in 768 divided by 3600. This will give you the number of miles traveled every second. Don't believe me? Look it up. Wikipedia is a great resource for information.

 In any case, this means that the sound from a lightning bolt is travelling about a mile every five seconds.  So that scary bolt is much closer than we were given to believe in our childhood.

To put this in perspective, the average human runs between five and eight miles per hour, so if you hear a lightning bolt that is only one second away, you could hypothetically jog to that location within two and a half minutes or less.  Or put another way, throw a baseball as far as you can toward the bolt, then run and pick it up.  Do this four more times and you will arrive at the bolt.

But I'm a lazy American, so I won't be doing any physical activity to reach the bolt.  So I will drive to the bolt at 60 mph.  At this speed, I would reach it in 12 seconds.  Count that on the freeway the next time you're out there and realize that's how close that bolt is to you when its sound is a second away.

Few more little tidbits about lightning:  Laying down is a bad idea, don't hide under a tree, don't stand on ladders, rubber tires in a car or the rubber on the soles of your shoe are not insulating you from a lightning strike, you can and should touch someone to help them after they've been struck by lightning, and finally and possibly most importantly: lightning often strikes the same place numerous times.